1. Field of the Invention
The invention relates to an X-ray exposure device, comprising an X-ray source and radiation detector including a slit diagram to form a fan-shaped radiation beam which is incident on an object to be examined.
2. Description of the Prior Art
In radiography it is generally desirable to mark the zone to be examined, i.e. the zone where an object to be examined is exposed to X-rays, prior to the exposure. The examination zone is generally so marked by coupling in light rays between the focus of the X-ray source and a stationary diaphragm, which light rays are confined by the diaphragm so as to define the examination zone in the plane of examination.
For slit radiography exposure techniques, however, this marking technique is not readily possible, because the primary diaphragm has a very narrow slit which forms the X-rays into a fan-shaped beam across the object to be examined.
Another possibility of applying the light for slit radiography exposure techniques couples light with mirrors located between the primary diaphragm and the object to be examined. An arrangement of this kind, however, has the drawback that the distance between the focus of the X-ray source and the primary diaphragm is thus inevitably reduced if the overall device is not to become too voluminous. The distance between the focus and the primary diaphragm, however, should be as large as possible in order to minimise the penumbral areas of the radiation beam in the examination plane. This is desirable in view of the need for suppression of scattered radiation of the primary beam transmission. Moreover, the coupling-in of light between the examination plane and the primary slit reduces the range for object positioning in the examination plane.